Electric Motor Having Improved Cooling

Abstract

An electric motor (1), in particular, an external rotor motor, has a stator (10) with a stator core (11), a non-rotatably attached shaft (20), that extends in the axial direction (A) of the motor, and a rotor bell (30), rotatably arranged relative to the non-rotatable shaft (20). The rotor bell (30) has cooling ribs in an open, spoke-like design rotatably mounted on the shaft (20) by at least one first stator-side bearing shield (31). A cooling device (40) is arranged between and connects the shaft (20) and the stator core (11). The cooling device (40) has a plurality of axial flow openings (41) arranged in the circumferential direction that causes cooling when the motor rotates during operation.

Claims

1. An electric motor, in particular an external rotor motor, comprises: a stator with a stator core, a non-rotatably mounted shaft, that extends in the axial direction (A) of the motor, and a rotor bell arranged rotatably with respect to the non-rotatable shaft; the rotor bell incudes cooling blades in an open, spoke-like design, the rotor bell is rotatably mounted on the shaft by at least one first stator-side bearing shield; a cooling device is arranged between and connects the shaft and the stator core, the cooling device has a plurality of axial flow openings arranged in the circumferential direction that causes cooling when the motor rotates during operation.

2. The electric motor according to claim 1, wherein the cooling device has an inner ring connecting the shaft and an outer ring connecting the stator core, and web-shaped connecting portions, extending in the radial direction, are formed integrally with the inner ring and the outer ring.

3. The electric motor according to claim 2, wherein the connecting portions have a central middle portion that is wider in the circumferential direction compared to the width in the adjacent web portions adjoining the middle portion on both sides.

4. The electric motor according to claim 1, wherein the cross section of the flow openings, viewed in the axial direction, is larger than the cross section of the regions located radially between the flow openings.

5. The electric motor according to claim 1, wherein the rotor bell forms a second rotor-side bearing shield, either as a separate bearing shield or integrally with the rotor bell, with which the rotor bell is rotatably mounted on the shaft.

6. The electric motor according to claim 1, wherein the stator-side bearing shield includes cooling blades that extend as radially extending spokes between a central bearing portion and a radially further outward bearing shield portion and openings are between the spokes.

7. The electric motor according to claim 1, wherein a stator flange is provided where the electric motor or the stator is mounted and the stator-side bearing shield is connected with the stator flange, in particular via a labyrinth seal.

8. The electric motor according to claim 1, wherein, viewed in the radial direction, electrical connection rings are provided between the cooling device and regions in the stator core provided for the stator coils, and connection wires attached in the circumferential direction for the electrical connection of the coils.

9. The electric motor according to claim 8, wherein four electrical connection rings are provided for the power supply.

Description

DRAWINGS

[0025] Other advantageous developments of the disclosure are included in the dependent claims and are represented in further detail in the following together with the description of the preferred embodiment of the disclosure with reference to the figures. In particular:

[0026] FIG. 1 is a cross-section view of an electric motor;

[0027] FIG. 2 is a perspective view of an electric motor with a stator-side bearing shield;

[0028] FIG. 3 is a plan view of the cooling device between the shaft and the stator core; and

[0029] FIG. 4 is a plan view of the cooling device between the shaft and the stator core.

DETAILED DESCRIPTION

[0030] The disclosure is explained below using selected exemplary embodiments explained in more detail. The same reference numbers denote structurally or functionally the same parts in the views.

[0031] FIG. 1 shows a cross-section view of a first exemplary embodiment of the electric motor 1 designed as an external rotor motor. The electric motor 1 is an external rotor motor that includes a stator 10 with a stator core 11 and a non-rotatably mounted shaft 20 that extends in the axial direction A of the motor.

[0032] A rotor bell 30 is rotatably arranged relative to the shaft 20. The rotor bell 30 has a tubular outer jacket AM and a stator-side bearing shield 31. The bearing shield 31 is attached to the outer jacket of the rotor bell 30 with fasteners B. The stator-side bearing shield 31 is mounted on the shaft 20 by bearings L. As can also be seen in FIG. 1, the electric motor 1 includes a stator flange 12.

[0033] FIG. 2 shows a perspective view of an electric motor 1 with a view of the stator-side bearing shield 31. The stator-side bearing shield 31 is formed with cooling blades that extend as radially running spokes 33, between a central bearing portion 34 and a bearing shield portion 35, lying radially further outwards, and openings 36 between the spokes 33.

[0034] At the end of the shaft 20, there is another bearing L. The rotor bell 30 is rotatably mounted to the bearing L, via a second rotor-side bearing shield 32. The rotor-side bearing shield 32 is also fastened via fasteners B to the rotor bell 30. It has a closed structure in order to ensure appropriate protection against environmental influences (e.g. degree of protection IP 54).

[0035] A cooling device 40 is arranged between the shaft 20 and the stator core 11 connecting the two parts. This design is such that when the motor rotates during operation, cooling of the stator is provided by the cooling device 40 with a plurality of axial flow openings 41 arranged in the circumferential direction. Thus, an air flow can be provided along the stator 10 and efficient cooling can be generated from the inside. The design is shown in more detail in FIG. 3. The cooling device 40 has an inner ring 42 connecting the shaft 20 and an outer ring 43 connecting the stator core 11. Both rings 42, 43 are integrally connected to one another via web-shaped connecting portions 44 extending in the radial direction. The material chosen is preferably aluminum or an aluminum alloy.

[0036] The connecting portions 44 have a central middle portion 45 that is wider in the circumferential direction compared to the width in the adjacent web portions 46 adjoining this middle portion 45 on both sides. The two sides are curved inwards along an arc and each have nose-shaped corner projections 47.

[0037] The effective cross section of the flow openings 41 in the axial direction is larger than the cross section of the regions located radially between the flow openings 41. Thus, a good and efficient flow is achieved.

[0038] As can be seen from FIG. 4, connecting rings 50 are provided between the cooling device 40 and regions in the stator core provided for the stator coils 37. The connecting rings 50 include connecting wires 51 for the electrical connection of the coils 37 in the rotation direction.

[0039] The implementation of the disclosure is not limited to the preferred exemplary embodiments specified above. Rather, a number of variants are conceivable which make use of the solution shown even in the case of fundamentally different embodiments. Thus, for example, the bearing shield 32 can also be formed integrally with the rotor bell 30.

[0040] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.